206 BULLETIN 121, UNITED STATES NATIONAL MUSEUM. 



on the breast. Doctor Chapman (1908a) describes the juvenal plum- 

 age as follows: 



In the succeeding specimen tlie second or juvenal plumage is essentially com- 

 plete, except upon the foreueclv, where it is just emerging. This bird is almost 

 uniform grayish-brown above ; the upper tail coverts are slightly browner ; the 

 exposed portion of the remiges audi rectrices show a somewhat frosted effect ; 

 the primaries are decidedly blackish ; the lower breast and abdomen are grayer 

 than the dorsal plumage; the upper breast (with which the throat feathers 

 would apparently agree) is decidedly browner. 



This plumage is apparently worn for about a year or until the 

 first complete postnuptial molt. I have seen young birds in this 

 Avholly brown plumage in July, September, January, and March and 

 have seen birds molting out of this plumage and into the white- 

 bellied adult plumage in May, in July, and in September. Young 

 birds therefore probably become indistinguishable from adults when 

 about a year and a half old. 



The small amount of material available for study makes it difficult 

 to arrive at any satisfactory conclusions as to the sequence of 

 plumages and molts of this species. I have seen but one adult in 

 full molt ; this is a July bird in which the primaries are in such con- 

 dition that the bird must have been practically incapable of flight. 



Food. — The food of the booby consists almost entirely of fish, 

 chiefly flying fish and mullets, many of them of large size, which it 

 is very expert in catching by diving. Audubon (1840) says: 



The expansibility of the gullet of this species enables it to swallow fishes 

 of considerable size, and on such occasions their mouth seems to spread to an 

 unusual width. In the throats of several individuals that were shot as they 

 were returning to their nests, I found mullets measuring seven or eight inches, 

 that must have weighed fuUy half a pound. 



Mr. Austin H. Clark (1903), writing of the habits of this species 

 on the Venezuela coast, says : 



They seemed to approach the land solely for the purpose of feeding, after 

 which they withdrew to open water. Just off Carupano there was a certain 

 spot to which every day came hundreds of sea birds of many species to fish. 

 Over one-half of this congregation were common brown pelicans and most of the 

 rest were these gannets. Overhead soared a score or more frigate birds, while 

 various gulls and terns composed the remainder. All the larger members of 

 this vast flock acted in perfect unison, wheeling about until a sufficient altitude 

 was obtained, all diving witli a great splash, then all slowly rising again to 

 repeat the performance. 



Single boobies may often be seen fishing in comioany with solitary pelicans, 

 imitating in every way the actions of their larger companions, diving at the 

 same time, and rising simultaneously. Mr. Outram Bangs has suggested to me 

 that perhaps the booby, being smaller and more active, finds a good fare in 

 the fish which the uncouth pelican fails to catch. 



Dr. Henry Bryant (1861) says of its feeding habits: 



The booby is, I think, the most expert diver that I am acquainted with ; no 

 matter in what position it may be, whether flying in a straight line, sailing 



